The present invention relates to a motor control device and a motor control method which control an output of a motor by controlling DC input voltage of an inverter which applies voltage to the motor. More specifically, the invention relates to a technique for reducing an inverter loss and an inverter size and enhancing the efficiency of the inverter without deteriorating the driving efficiency of the motor.
Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 2001-314095, there is a known motor control device which controls a rotation speed of a motor by switching between a region where PWM (Pulse Wide Modulation) control is performed in a state where the DC input voltage of an inverter is maintained at a constant voltage, and a region where PAM (Pulse Amplitude Modulation) control is performed while varying the DC input voltage of the inverter by a pressure rising circuit, according to a driving state of the motor. According to such a motor control device, the motor can be driven under an optimal condition according to the operating state of the motor, and the motor can be operated efficiently with small vibration.